Speedometer-drive gear.



E. A. LARSON.

SPEEDOMETER DRIVE GEAR, APPLICATION FILED MAY :7. 1913.

1,182,022. Patented May 9,1916.

zcs QaZyas UNITED STATES. PATENT OFFICE.

EDWARD A. LARSON, OF CHICAGO, ILLINOIS, ASSIGNOR TO STEWART-WARNERSPEEDOMETER CORPORATION, OF CHICAGO, ILLINOIS, A CORPORATION OFVIRGINIA.

SPEEDOMETER-DRIVE GEAR.

Application filed Kay 17, 1913.

To all whom it may concern Be it known that I, EDWARD A. LARSON, acitizen of the United States, residing at Chicago, in the county of Cookand State of Illinois, have invented new and useful Improvements inSpeedometer-Drive Gear, of which the following is a specification,reference being had to the accompanying drawings, forming a partthereof.

The purpose of this invention is to provide simple and efficient gearingfor transmitting rotation proportional to the speed of the road wheelsof a motor vehicle to a V speedometer or other travel-indicating devicemounted in any convenient position upon the vehicle, preferably on thedashboard. 7

The invention consists of the features and elements described and shownin the drawings as more particularly indicated in the claims.

In the drawings :-Figure 1 is a partial plan view of an automobilechassis showing the drive gear installed thereon. Fig. 2 is a detailview showing the transmission gear of the vehicle and the speedometerdrive device applied thereto. Fig. 3 is an enlarged detail section takenas indicated at line 33 on Fig. 2. Fig. 4 is a section taken asindicated at line on Fig. 3. Fig. 5 is a detail elevation looking in thedirection of the arrows 5-5 on Fig. 1.

Tu most motor vehicles the speed-change gearing through which the ratioof the engine speed to the road wheel speed is varied contains anelement whose rotation bears a fixed relation to the rotation of suchroad wheels, and the present device is designed to connect a speedometeror other travel-indicating device with such an element in thetransmission train. As detailed in Fig. 2, the transmission selected forillustrative purposes comprises the engine shaft, 1, the propellershaft, 2, which is permanently coupled with the road wheels, and a sideshaft or counter shaft, 3, through which the rotation of the engineshaft, 1, is transmitted to the propeller haft, 2, in a well understoodmanner through spur gears, except in the case of direct drive, and atall times, even in this latter case the counter shaft, 3, is rotativelyconnected with the propeller shaft, 2, by a pair of gears, 4 and 5. Thespeed of its rotation consequently bears a fixed relation to therotation of the Specification of Letters Patent.

Patented May 9, 1916.

Serial No. 768.259.

road wheels, 6, 6, and this counter shaft, 3, is, therefore. aconvenient element from which to derive motion for the speedometer, A,for purposes of speed measurement and indication.

The present device consists of a padlike gear housing, B, designed tofit exteriorly upon the end of the transmission housing, C, with theprojecting tang, D of the shaft, D, engaged in a slot diametrically cutacross the end of the counter shaft, 3. A spiral gear. D on the shaft.D, transmits the rotation thus obtained to a spiral gear, E on atransversely extending shaft, E, which is provided at one end with aterminal tang, E through which it may be coupled with a standardflexible or jointed shaft such as indicated at F, and extending to thespeedometer, A. By this construction the drive gears, D and E areembodied in a practically unitary fitting which may be applied to thetransmission housing, C, with a minimum of labor, and without in anymanner opening either of the two devices which are connected; viz., thehousing, C, and the pad, B, and con nected casing of the flexible shaft,F, both of these members, a will be understood, be ing constructed so asto be filled, and being filled as a part of the process of construction,with a lubricant which is prevented from escaping", because the saidmembers, respectively, have no openings except those through which theshafts protrude and which are closed by such protruding shafts. Thisresults in a very compact arrangement of the speedometer driving means;and as indicated in Fig. 5 this arrangement requires little more than. asingle bend in the flexible shaft, F. Preferably the gear housing. B,includes the split socket, B and clamp screw, B by which the end of thehousing F of the flexible shaft. F, may be secured. As indicated inFigs. 3 and 4:, the gear housing, B, embodies in a single casting thechamber for the gears, D and E being supplemented merely by two plugs, Band B, which are provided for convenience in assembling and arepreferably made as driving fits in the casting, so as to be permanentlyforced into place when the device is made up.

I claim 1. In a motor vehicle, in combination, a transmission. gearingcomprising a casing and a gear train therein having a- Shaft exposed forengagement through an exterior wall of the casing; 21 housing for asupplement-a1 gear train, and a train therein comprising a shaft Whichprotrudes from the housing, and a second shaft which is exposed forengagement through an exterior wall of the housing. said casing andhousing having the exterior surfaces of their respective Walls aroundthe axes of said respectively exposed shafts, matched to seat one uponthe other, said exposed shaftsheing matched for engagement one With theother when said walls are so seated one upon the other.

2., In a motor vehicle, in combination, a transmission gearingcomprising a casing, and a gear train therein having a shaft whichterminates in an exterior Wall; of the casing; 21 housing for asupplemental gear train which comprises a shaft protruding I Copies 01'-thil patent may be obtained for from the housing, and a second shaftwhich protrudes through an exterior Wall of the housing, the exteriorsurfaces of said casing and. housing encompassing the axes of the shaftsterminating in and protruding from them respectively being matched forseating one upon the other, the wall of the easing. being apertured toadmit the end of the shaft protruding from the housing, and the saidshafts being matched for driving engagement with each other When saidcasing and housing are matched one upon the other. I

Iriv'testi'mony whereof I have hereunto set my hf nd at Chicago,Illinois, this 14 day of EDYVAR'D A. LARSON. Vitnesses C. P. Sir-urn, S.Henson five cents each, by addressing the Gommissipner of Patent.Washington, D: Q. 1

